Field of the Invention
The present invention generally relates to data storage, and more particularly, some embodiments relate to Storage Area Network (SAN) systems and methods.
Description of the Related Art
The storage and retrieval of data is an age-old art that has evolved as methods for processing and using data have evolved. In the early 18th century, Basile Bouchon is purported to have used a perforated paper loop to store patterns used for printing cloth. In the mechanical arts, similar technology in the form of punch cards and punch tape were used in the 18th century in textile mills to control mechanized looms. Two centuries later, early computers also used punch cards and paper punch tape to store data and to input programs.
However, punch cards were not the only storage mechanism available in the mid 20th century. Drum memory was widely used in the 1950s and 1960s with capacities approaching about 10 kb, and the first hard drive was developed in the 1950s and is reported to have used 50 24-inch discs to achieve a total capacity of almost 5 MB. These were large and costly systems and although punch cards were inconvenient, their lower cost contributed to their longevity as a viable alternative.
In 1980, the hard drive broke the 1 GB capacity mark with the introduction of the IBM 3380, which could store more than two gigabytes of data. The IBM 3380, however, was about as large as a refrigerator, weighed ¼ ton, and cost between approximately $97,000 to $142,000, depending on features selected. In contrast, contemporary storage systems now provide storage for hundreds of terabytes of data, or more, for seemingly instantaneous access by networked devices. Even handheld electronic devices such as digital cameras, MP3 players and others are capable of storing gigabytes of data, and modern desktop computers boast gigabytes or terabytes of storage capacity.
With the advent of networked computing, storage of electronic data has also expanded from the individual computer to network-accessible storage devices. These include, for example, optical libraries, Redundant Arrays of Inexpensive Disks (RAID), CD-ROM jukeboxes, drive pools and other mass storage technologies. These storage devices are accessible to and can be shared by individual computers using such traditional networks as Local Area Networks (LANs) and Wide Area Networks (WANs), or using Storage Area Networks (SANs). These client computers not only access their own local storage devices but also network storage devices to perform backups, transaction processing, file sharing, and other storage-related operations.
Network bandwidth is limited and can be overloaded by volumes of data stored and shared by networked devices. During operations such as system backups, transaction processing, file copying and transfer, and other similar operations, the network communication bandwidth often becomes the rate-limiting factor.
SANs, in particular, are networks designed to facilitate transport of data to and from network storage devices, while addressing the bandwidth issues caused by large volumes of data stored and shared on the network storage devices. Specifically, SANs are network architectures that comprise a network of storage devices that are generally not accessible by nodes on a traditional network (e.g., LAN or WAN). As such, a SAN implementation usually requires two networks. The first network is a traditional network, such as a LAN, designed to transport ordinary traffic between individual network computers (i.e., nodes). The second network is the SAN itself, which is accessible by individual computers through the SAN but not through the traditional network. Typically, once a SAN storage device (also referred to as a SAN storage node) is remotely attached to an individual computer over a SAN, it appears and functions much like a locally attached storage device (as opposed to appearing and functioning as a network drive).
By utilizing a SAN as a separate network for storage devices that perform bandwidth-intensive operations (e.g., backups, transaction processing, and the like), the SAN storage devices realize improved bandwidth among themselves and with traditional computers attached to the SAN. Additionally, when storage devices and traditional nodes communicate over the SAN, more bandwidth-intensive operations are performed over the SAN rather than a LAN, leaving the LAN to handle only the ordinary data traffic.
FIG. 1 illustrates an example of a traditional SAN implementation 10. There are multiple client nodes 15, 18, and 21 networked together using a LAN 1 which allows communication of ordinary data traffic between the nodes (15, 18, 21). Storage devices 12 are connected together through SAN 13, which provides high bandwidth network capacity for bandwidth-intensive data operations to and from the storage devices 12. As illustrated, client nodes 18 and 21 are also connected to SAN 13, allowing them high bandwidth data access to the storage devices 12. As discussed above, by utilizing the SAN to perform high bandwidth data access, the client nodes are not only moving bandwidth-intensive data operations from the LAN 19 to the SAN 13, but also accessing the data at higher data rates than are typically available on a traditional network such as LAN. Typically, SANs utilize high bandwidth network technologies, such as Fiber Channel (FC), InfiniBand, Internet Small Computer System Interface (iSCSI), HyperSCSI, and Serial Attached SCSI (SAS), which are not commonly utilized in traditional networks such as LANs.